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Firefox opens with ads

  • 6 replies
  • 1 has this problem
  • 31 views
  • Last reply by msnicolaou

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For a few days now, whenever I boot up my PC and I click on Firefox to start, instead of starting with the homepage it automatically starts with some sort of ad, usually to update Flash or something. I didn't screencap any of the addresses, but they're definitely random-looking ad addresses. And as far as I know I haven't installed or downloaded anything sketchy to cause this. Any way of remedying this?

Chosen solution

Hmm, it hints at some kind of malware, but I'm not sure how it is changing the startup page just once without modifying the shortcut.

You could supplement your regular security scanner with one or more of the well-regarded ones described in the support article: Troubleshoot Firefox issues caused by malware. Those are generally either free or offer a free trial.

You also could look at your startup programs to see whether there is anything unexpected. Microsoft has a useful utility for this: https://docs.microsoft.com/en-us/sysinternals/downloads/autoruns

You also could look at the Windows Task Scheduler / Scheduled Tasks. I'm not sure how to tell which ones run at startup.

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All Replies (6)

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That's suspicious. Could you check these things:

(1) Modified Home Page Setting?

Firefox allows opening a custom URL at startup. Does yours work correctly when you click the Home icon, press the Alt+Home keyboard shortcut, or launch a new window using Ctrl+n? If those also behave suspiciously, the custom URL could be the issue. See: How to set the home page.

(2) Hacked Firefox Program Shortcut?

If this problem only occurs when you use your shortcut, check whether it has been modified with an additional URL. Either:

  • Right-click a Firefox desktop shortcut, then click Properties
  • Right-click a Firefox icon pinned to the Taskbar then right-click Mozilla Firefox, then click Properties

Windows should show the Shortcut tab and select the Target field. The Target usually is along the following lines:

  • "C:\Program Files\Mozilla Firefox\firefox.exe"
  • "C:\Program Files (x86)\Mozilla Firefox\firefox.exe"

If there is anything extra after that which you did not put there, you can remove it.

(3) Rogue Add-on?

One possible culprit would be an extension. You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

  • Ctrl+Shift+a (Mac: Command+Shift+a)
  • "3-bar" menu button (or Tools menu) > Add-ons
  • type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. On the right side, find the "Manage Your Extensions" heading.

If there is at least one extension before the next heading -- "Recommended Extensions" -- please continue:

Then cast a critical eye over the list below that heading. Any extensions Firefox installs for built-in features are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious or that you just do not remember installing or why? If in doubt, disable (or remove). For your privacy and security, don't let mystery programs linger here.

Any progress so far?

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jscher2000 said

That's suspicious. Could you check these things: (1) Modified Home Page Setting? (2) Hacked Firefox Program Shortcut? (3) Rogue Add-on? Any progress so far?

1. It's clear 2. It's clear 3. I'm pretty sure there's nothing weird or unknown here and they all have the little icon that says it meets Firefox's standards for security and such.

I forgot to mention that this issue only happens when I boot up the PC and open Firefox for the first time (in case that hints at anything).

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Chosen Solution

Hmm, it hints at some kind of malware, but I'm not sure how it is changing the startup page just once without modifying the shortcut.

You could supplement your regular security scanner with one or more of the well-regarded ones described in the support article: Troubleshoot Firefox issues caused by malware. Those are generally either free or offer a free trial.

You also could look at your startup programs to see whether there is anything unexpected. Microsoft has a useful utility for this: https://docs.microsoft.com/en-us/sysinternals/downloads/autoruns

You also could look at the Windows Task Scheduler / Scheduled Tasks. I'm not sure how to tell which ones run at startup.

Helpful?

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jscher2000 said

Hmm, it hints at some kind of malware,

I've tried everything now and removed some random things that were detected but nothing works. Here's a new, strange development though: I removed Firefox, installed Google Chrome, set that as the default browser, and re-downloaded Firefox. Now the same issue is happening with Chrome, which makes me think that whatever malware it is, targets whatever is set as the default browser... Has that been reported before?

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msnicolaou said

I removed Firefox, installed Google Chrome, set that as the default browser, and re-downloaded Firefox. Now the same issue is happening with Chrome, which makes me think that whatever malware it is, targets whatever is set as the default browser... Has that been reported before?

Maybe? The article lists specialized malware diagnosis and cleanup forums for hard cases. You could try one of those.

Helpful?

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jscher2000 said

msnicolaou said

I removed Firefox, installed Google Chrome, set that as the default browser, and re-downloaded Firefox. Now the same issue is happening with Chrome, which makes me think that whatever malware it is, targets whatever is set as the default browser... Has that been reported before?

Maybe? The article lists specialized malware diagnosis and cleanup forums for hard cases. You could try one of those.

I just got it! So since Malwarebytes's AdwCleaner didn't work, it did advertise on the side its "Premium" to try for free and it actually worked. Found several obnoxious "ad startup" files scattered around and resolved the problem (as far as I know). Thanks a lot for your help and sticking with me. Much appreciated. I guess spreading the Good Word of Malwarebytes Premium would be beneficial since it outperformed everything else.

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